《《Tunable Dirac cone in the topological insulator Bi2-xSbxTe3-ySey》.pdf

ARTICLE Received 19 Aug 2011 | Accepted 9 Dec 2011 | Published 17 Jan 2012 DOI: 10.1038/ncomms1639 Tunable Dirac cone in the topological insulator Bi sb Te se 2-x x 3-y y 1 2 1 2 2 2 1,2 3 T. Arakane , T. sato , s. souma , K. Kosaka , K. nakayama , m. Komatsu , T. Takahashi , Zhi Ren , 3 3 Kouji segawa Yoichi Ando The three-dimensional topological insulator is a quantum state of matter characterized by an insulating bulk state and gapless Dirac cone surface states. Device applications of topological insulators require a highly insulating bulk and tunable Dirac carriers, which has so far been difficult to achieve. Here we demonstrate that Bi sb Te se is a system that simultaneously 2-x x 3-y y satisfies both of these requirements. For a series of compositions presenting bulk-insulating transport behaviour, angle-resolved photoemission spectroscopy reveals that the chemical potential is always located in the bulk band gap, whereas the Dirac cone dispersion changes systematically so that the Dirac point moves up in energy with increasing x, leading to a sign change of the Dirac carriers at x~0.9. such a tunable Dirac cone opens a promising pathway to the development of novel devices based on topological insulators. 1 WPI Research Center, Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan. 2 Department of Physics, Tohoku University, Sendai 980-8578, Japan. 3 Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan. Correspondence and requests for materials should be addressed to T.S. (email: t-sato@arpes.ph